I am not sure why your User Accounts link(in category view?)is not working. Have you tried switching to Clasic View? There is a link for that in the left pane. I suspect the icon will not be in Classic View at all.

Another way to access the User Accounts is to right-click on My Computer and select properties. Click advanced, and look for a link to user accounts. Alternately, you could look under Help and there should be a link.

Some aspects of user accounts can be edited by clicking Start->Run... and entering "controluserpasswords2" without the quotes.

Sorry I don't have a real fix for you, but post back here is any of my suggestions work, don't work, or if you find a resolution.